Method of treating portland and similar cement.



HOWARD J. FORGE, 0F S CRAN'EON, PENNSYLVANIA.

METHOD OF TREATING PORTLAND AND SIMILAR CEMENT.

No Drawing.

Specification of Letters z'atent.

Patented Feb. 3, 1914 Application filed September 13, 1912. Serial No. 720,157.

To all whom it may concern: Be it known that I, HOWARD J. FORGE,

a citizen of the United States, residing at Scranton, in the county of Lackawanna and State. of Pennsylvania, have invented a new and useful Improvement in Methods of Treating Portland and Similar Cements, of which the following is a specification.

In the methods of testing'Portla'nd and similar cement for tensile strength heretofore practised, the cement was made into briquets having a cross section of one square inch, then allowed to set for twenty-four hours in a moist closet, and then broken in a machine for testing tensile strength. Similar briquets have also been subjected to a boiling test before being broken, which test consisted in boiling the briquets under atmosphericjiressure for the purpose of ascertaining whether or not the briquets would become cracked or disintegrated in boiling water. withstood these tests have nevertheless failed when made into concrete, for thereason that they contained a considerable percentage of large or coarse granules which did not readily absorb water or become hydrated in mixing the cement with water preparatory to testin samples of the cement and which afterwar when the cement had been used for making concrete, had absorbed water and caused a swelling, disruption or disintegration of the concrete.

The object of this invention is to provide a test which will efiectually show the character of the cement as to permanency or durability when made into concrete.

In practising this invention briquets are made up of neat cement with a sufficient quantity of water to make a fairly plastic mass. These briquets are made in the usual brass molds having a cross section of one square inch and are placed in a moist closet where they are kept for twenty-four hours. At the expiration of this time a number of these briquets, usually three, are broken in a testing machine, and anotherlike number of the same briquets are boiled under pressure for about two hours. The pressure is preferably about 20 atmospheres or 285 pounds per square'inch, which pressure is conveniently produced by placing the briquets in an autoclave or digester which contains water of about 7 0 F., then closing the autoclave and then raising the temperature of the water by means of a gas flame or Cements which .have successfully other suitable source of' heat. usually about an hour to reachia pressure of 285 pounds and this pressure is maintainedfor about an hour. Upon the expiration'of this time the flame is extin uishedfl the pressure is blown ofi, whic usually takes about twenty minutes. The biiqhiijets are then taken from the water and fit" t -ey have not been injured by the boiling they are placed in a moist closet for about half an hour. The briquets are then weighed and the gain or loss in weight is noted and the briquets are then broken in a testing machine.

' It has been found that only cementwhich is sound in every way and suitable for producing a sound and lasting concrete will resist boilin under pressure successfully. Cements w ich will pass this test successfully are such which have been carefully manufactured by grinding the ingredients very finely, for instance so that 85 per cen of the ound material will pass through a' sieve 200 mesh to the inch, then calcined or burned at a high temperature, for instance 2700 F., and then again ground to about the same fineness, orcements which are made of ingredients which have been thoroughly seasoned for several months after calcination. Inferior cements which are liable to produce unreliable concrete will crack or disintegrate when boiled under pressure or show a decided loss in tensile strength. Pract-icehas-shown that a pres It takes testing after a treatment of a few hours,

duration.

A satisfactory quality of cement will show a considerable" increase or" tensile,strength after having been boiled under pressure as compared with the same cement which has not been so treated, the increase being twenty-five per cent. 'or more and an unsatisfactory quality of cement willcrumble or disintegrate under the treatment herein described. The tensile strength of the cement treated under pressure should not be less "than 400 pounds per square inch. The gain in weight by the cement during the boiling under pressure should not exceed one per cent.

The same test is also desirable for aseertaining the character of the cement with reference to expansion. For that purpose expansion bars are made of the cement mixed with water in the usual way with across secticn of about 1 square inch and a length of about 6 inches. The bars are then placed in a moist closet and at the expiration of twenty-four hours are carefully measured. They are then placed in the autoclave and lfoiled under pressure as above described, and at the end of that treatment are again i'ueasnrcd. Cement-s which are constant in volume should not show expansion of over one-half of one per cent. when tested under the above described conditions, The pres sures mentioned herein are measured from the atmospheric pressure as the zero.

I claim as my invention:

1. In the method of preparing solid bodies of Portland or similar cement for testing the same the herein described treatment which consists in boiling such cement bodies under a pressure which exceeds fifty pounds to the square inch.

2. In the method of preparing solid bodies of Portland or similar cement the herein described treatment which consists in boiling such cement bodies under a pressure up- PI'OXlIIItLtlD two hundred and eighty-five pounds to the square inch.

Witness my hand, this 7 day of Sept.

HOWARD J. FORCE. Witnesses D. R. Reuse, C. H. FARNI-IAM. 

